At least 14 moviegoers were killed and 50 injured at a cinema in the Colorado city of Aurora in the Denver suburbs. They were attending a midnight showing of the new Batman film, The Dark Knight Rises.

The theater was packed with a lot of people, many of them young fans, at the time the shooting started, 9news reports. The violence erupted some 15 minutes after the movie began, witnesses said.

Police say that the assailant initially opened a gas canister. Witnesses recounted hearing a hissing sound and smoke, and then the shooting started.

Some say that when they first heard the gunfire, they thought it was some new type of special effect.

“It was chaotic, it was surreal, it was like in a movie,” one of the witnesses told 9news Denver TV station.

Initial media reports suggested that two gunmen were involved in the rampage. But police later said there was only one person involved as far as they know. The gunman was carrying a rifle and a handgun at the time of his arrest, police said at a media conference. One suspect was taken into police custody.

Witnesses reported seeing a tall, shotgun-wielding man clad in body armor and wearing a gas mask in the theatre. The attacker have set off some kind of a tear gas canister.

A d v e r t i s e m e n t

An apartment building was evacuated after the suspect told police there were explosives planted there following his apprehension. So far police have failed to find any traces of the alleged bombs.

Police responding to the shooting evacuated the area over fears that an explosive device might be on the premises.

Ten of the victims were killed right on the spot while four others died from injuries in hospital.

Aurora medical services were alerted to attend to the large number of injured. At least 50 people have been taken to hospital following the shooting, although it is not clear yet how many of them are in serious condition.

The FBI is considering raising the national security level nationwide following the shooting, Sky News says citing its sources.